By the same token, it is unfair to the moderators that they are unable to see over what may very well be community-wide issues. To mitigate both of these, we've created a separate moderator inbox for each reddit which can be messaged by composing a PM to "#redditname" (with the hashmark stolen from IRC parlance).
So, for now on, to reach the admin's box, send a message to "#reddit.com" and we'll get back to you. For other reddits, we've added a handy link to the moderator box. From a moderator's viewpoint, we've make a UI tweak to differentiate your moderator inbox from your regular inbox:
And a new orangered alien for when you have moderator mail:
Clicking on the alien will bring you to your moderation inbox. In this view, you'll see the messages to all of the reddits you moderate organized with the newest on top. 
Clicking on the name of the reddit (in the blue bubble on the top left) will bring you to a view that shows messages for that reddit alone. This view is also accessible from the "moderator toolbox" on each of your reddits. One thing to note in responding to these messages: when you participate on a message thread initiated by a user, everything in the conversation will be sent back to the user as an implicit CC.
tldr: Don't message one moderator, message all moderators.
